KR20100029319A - Method and apparatus for multicast and broadcast service with header compression in wideband communication system - Google Patents

Abstract

PURPOSE: A method and apparatus for in the broad band wireless communications system, the header compression is applied to multicast and broadcast service of the broad band wireless communications system, mode and state of the virtual compressor are decided through SMC. In that way ROHC is applied to the MBS service flow. CONSTITUTION: If a MBS(Multicast Broadcast Service) service flow is added, the base station is created MBS(500, 502). The MBS has the ROHC(Robust Header Compression) service flow. A base station registers the new compressor which becomes in a virtual compressor list(504). The base station transmits the IR packet through the SMC(Secondary Management CID)(506). The feedback packet is received through SMC, the base station discontinues the IR packet transmission through SMC(508, 510).

Description

METHOD AND APPARATUS FOR MULTICAST AND BROADCAST SERVICE WITH HEADER COMPRESSION IN WIDEBAND COMMUNICATION SYSTEM}

The present invention relates to a multicast and broadcast service (MBS) in a broadband wireless communication system, and more particularly, to a method and apparatus for applying ROHC (Robust Header Compression) to the MBS service.

Packet data service provided in the current mobile communication system is provided by the user in a single transmission (Unicast) method to the network. That is, data is sent and received by designating a specific user's address, and an access network provides a service by allocating a band for data transmission to the corresponding user. Therefore, in the current system, services are provided in a conventional unicast manner so that different users simultaneously receive the same service. However, this method is a waste of resources between the network and the radio, and causes a load on the system.

Accordingly, a solution to the problem is a broadcast (Multicast and Broadcast Service: MBS) service. The broadcast service provides a desired service while saving resources to users who want to receive the same service at the same time, and can provide the same data service as before.

1 illustrates a broadband wireless communication system for a multicast and broadcast service (MBS) service.

Referring to FIG. 1, access control routers (ACRs) 140 and 142 are controllers for controlling a radio access station (RAS) and managing mobility of terminals 170, 172, and 174. The ACRs 140 and 142 connect the core network 100 and the broadband wireless communication network. That is, it handles IP packet transmission and reception between networks and takes charge of the interface with the core network 100 such as Mobile IP, AAA, DNS, DHCP, and the like.

Packets generated from the MBS content server 120 are transmitted to the corresponding ACRs 140 and 142 through the core network 100, and the ACRs 140 and 142 transmit the L2SW (packet) packets arriving from the core network 100. Layer 2 SWitch (150 to 156) is sent to the corresponding RAS (RAS1 to RAS40).

The RAS transmits a packet to the terminal 170, 172, or 174 through a wireless channel. In addition, the packets generated by the terminals 170, 172, and 174 are transmitted to the corresponding RAS through a wireless shared channel.

MBS service is a service that transmits broadcast or multicast information to multiple terminals at the same time. Multiple RASs simultaneously transmit the same content using the same radio resources. That is, the plurality of RASs receive some content from the MBS content server 120 and transmit the same content to the corresponding terminal. For example, RAS 1 to RAS 9 in MBS Zone 1 simultaneously transmit the same content to the terminal, RAS 10 to RAS 21 in MBS Zone 2 simultaneously transmit the same content to the terminal, and RAS in MBS Zone 3 22 through RAS 40 simultaneously transmit the same content to the terminal.

In the case of a multi-BS MBS service, in order for several terminals to simultaneously receive data bursts transmitted by multiple base stations, the multiple base stations must be synchronized in transmitting MBS data bursts. Base stations synchronized with each other to support the MBS service may configure the MBS zone. A base station in one MBS zone should be synchronized in the corresponding MBS data burst transmission, and this MBS zone is divided into MBS zone Identifier (hereinafter referred to as MBS zone ID).

Meanwhile, the MBS service is also performed based on the IP packet. Depending on the type of application used, IP / UDP (User Datagram Protocol) / RTP (Real Time Protocol), IP / UDP, or IP may be transmitted only. The MAC (Media Access Control) PDU (Packet Data Unit) transmitted and received between the base station and the terminal has the configuration as shown in FIG.

2 illustrates a general MAC PDU configuration diagram.

Referring to FIG. 2, the MAC PDU configuration diagram includes a MAC header 200, a header 210 of an upper layer such as IP and UDP, and finally a payload 220. The MBS service transmits the same content to multiple subscribers at the same time, so a lot of radio resources are needed at the same time.

To this end, a header compression technique such as ROHC (RObust Header Compression) is applied. The ROHC is divided into Profile 1 compressing IP / UDP / RTP, Profile 2 compressing IP / UDP, Profile 3 compressing IP / ESP (Encapsulating Security Payload), and Profile 0 sending without compression. (See RFC3095 documentation). For header compression, the packet sender compresses according to the profile in the ROHC to reduce the size of the upper layer header 210, and the packet receiver decompresses the received packet to restore the header before compression. A block that functions to reduce the size of a packet header at a packet sender is called a compressor block, and a block that restores the compressed packet header to its original form at a packet receiver is called a decompressor block. .

As described above, when using Voice over Internet Protocol (VoIP) or another specific application, when the ROHC technique is applied, about 90% of the upper layer header 210 may be compressed and transmitted. If the MBS service is used, a plurality of users receive the same broadcast service at the same time, and thus use many radio resources simultaneously. In this case, if the compression is applied by applying the ROHC, radio resources can be saved. However, in the current IEEE 802.16 standard, ROHC cannot be applied to MBS service. The terminal and the base station supporting the MBS service complete the registration procedure, and the DSx process for the service is performed. The DSx process is a process of delivering a multicast connection ID (hereinafter referred to as MCID) for an MBS service to a terminal, and includes an MBS zone ID and an MCID in a DSA message. The terminal can distinguish the data burst transmitted through the MBS zone through the MBS zone ID and the MCID information. To apply ROHC, the ROHC may be applied to each service flower through a DSx process.

The MBS map message includes information on the MBS data bursts transmitted through the MBS subframe, and the MBS data burst can be distinguished through the MCID. The terminal may distinguish and decode the MBS data burst corresponding to the terminal through the MBS map message. MBS signals are received from several base stations in the MBS zone, and several base station signals belonging to the same Multi-BS MBS service are synchronized with each other in terms of time and frequency. That is, all base stations belonging to the same MBS zone use the same location and physical environment variables of the transmitted data burst. In other words, when terminals in the same MBS zone receive the same broadcast, all received data must be identical. However, even if the same data is transmitted, the ROHC must perform compression for each service flow. Because of this, even ROHC with the same algorithm can be compressed differently. The service flow that finishes the DSx process to receive the MBS service starts with the IR state of the U mode which is the first start when the ROHC is applied, which is likely to be different from the ROHC mode and state of other terminals receiving the same broadcast. Therefore, synchronization is lost in MBS data burst transmission, which is one of the biggest reasons why ROHC cannot be applied to MBS service.

An object of the present invention is to provide a method and apparatus for applying ROHC to MBS service in a broadband wireless communication system.

Another object of the present invention is to provide a method and apparatus for saving radio resources by applying ROHC to MBS service in a broadband wireless communication system.

According to a first aspect of the present invention for achieving the above object, a method for operating a base station for applying a Robust Header Compression (ROHC) to a multicast & broadcast service (MBS) service in a broadband wireless communication system, the service to the MBS service When the flow is generated, transmitting a predetermined number of initial ROHC packets through a second management connection identifier (SMC), receiving a feedback packet for the predetermined number of initial ROHC packets, and After receiving the feedback packet, characterized in that it comprises the step of performing a general operation to the synchronized ROHC packet.

According to a second aspect of the present invention for achieving the above object, a method for operating a terminal for applying Robust Header Compression (ROHC) to a Multicast & Broadcast Service (MBS) service in a broadband wireless communication system, the second management connection Receiving a predetermined number of initial ROHC packets through a Secondary Management CID (SMC), transmitting a feedback packet for the predetermined number of initial ROHC packets, and transmitting the feedback packets And performing a general operation with the ROHC packet.

According to a third aspect of the present invention for achieving the above objects, in the base station for applying the Robust Header Compression (ROHC) to the MBS (Multicast & Broadcast Service) service in a broadband wireless communication system, the service flow is in the MBS service When generated, a transmitter for transmitting a predetermined number of initial ROHC packets through a second management connection identifier (SMC), a receiver for receiving feedback packets for the predetermined number of initial ROHC packets, and the feedback packets. After receiving, characterized in that it comprises a ROHC engine for performing a general operation to the synchronized ROHC packet.

According to a fourth aspect of the present invention for achieving the above objects, a terminal for applying a Robust Header Compression (ROHC) to a Multicast & Broadcast Service (MBS) service in a broadband wireless communication system, the second management connection identifier ( A receiver for receiving a predetermined number of initial ROHC packets through a Secondary Management CID (SMC), a transmitter for transmitting a feedback packet for the predetermined number of initial ROHC packets, and a synchronized ROHC packet after transmitting the feedback packets. It characterized in that it comprises a ROHC engine for performing a general operation.

As described above, the ROHC can be applied to the MBS service flow by determining the mode and state of the virtual compressor through the SMC in the broadband wireless communication system. In addition, it is possible to save radio resources by applying ROHC.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, detailed descriptions of related well-known functions or configurations will be omitted if it is determined that the detailed description of the present invention may unnecessarily obscure the subject matter of the present invention. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification.

Hereinafter, a method and apparatus for applying ROHC (Robust Header Compression) to a multicast & broadcast service (MBS) service in a broadband wireless communication system will be described.

ROHC has three operation modes: U (Unidirectional) mode, O (bidirectional Optimistic) mode, and R (bidirectional reliable) mode. U mode is a mode in which the feedback from the decompressor to the compressor is not used, and in O mode and R mode, feedback such as ACK, NACK, and STATIC-NACK is transmitted from the compression-restore to the compressor. This allows for more reliable and effective compression. Feedback messages include ACK, NACK, and STATIC-NACK. The ACK sends a ACK to the compressor by the compression-restorer when the packet is successfully decompressed. The ACK indicates that the Compressor-Restore normally decompressed the packet sent by the compressor. NACK tells the compressor that the Compressor-Restore did not decompress normally, and that the Compressor receives more information by sending a compressed packet with a cyclic redundancy check (CRC) or by transitioning its state. Send a compressed packet. The compressor and the compression-restorer operate in three states each in each mode. The compressor operates in three modes: Initialization and Refresh (IR), First Order (FO), and Second Order (SO). The Compressor-Restorer is configured to "No Context", "Static Context", " It operates with three states of "full context".

3 shows a state transition diagram of the compressor in U mode.

Referring to FIG. 3, in the U mode, state transition is performed using an optimistic approach 330, 335, 340 and timers 305, 315, 325 without feedback.

For example, the transition state of the compressor transitions to the FO state 310 in accordance with an optimistic approach 330 if it is confident that the compression-restorer has received enough information in the initial IR state 300 and correctly restored the compressed packet. do. Then, in the FO state 310, if the compression-restorer has received enough information and is convinced that it has correctly restored the compressed packet, it transitions to the SO state 320 according to the optimistic approach 335. In addition, if the compression-restorer in the initial IR state 300 is confident that it has sufficiently received information and correctly restored the compressed packet, it may transition to the SO state 320 in accordance with an optimistic approach 340.

On the other hand, if the compression-restorer does not correctly recover the compressed packet in the SO state 320, the state transitions to the FO state 310 according to the timer 315. Thereafter, if the compression-restorer does not correctly recover the compressed packet in the FO state 310, it transitions to the IR state 300 according to the timer 305. In addition, if the compression-restorer in SO state 320 is confident that it has received enough information and correctly restored the compressed packet, it may transition to IR state 300 in accordance with timer 305.

As described above, the compressor uses an Optimistic approach 330, 335, 340 and timers 305, 315, 325 to generate an IR state 300, a FO state 310, and an SO state 320. Transition to. Here, as in the MBS service, when several terminals simultaneously receive the same data burst transmitted by several base stations, the corresponding base station that is different from the corresponding terminal that is different from the transition state in the ROHC applied in the service flow between the terminal and the base station The transition state in the ROHC applied in the service flow between them cannot be the same. That is, since a plurality of terminals receive the same data in the MBS service, the same ROHC algorithm should be applied to the plurality of terminals. For example, when the base station transmits the same MBS data to the first terminal, the second terminal, and the third terminal, the service flow between the base station and the first terminal is called a first service flow, and the base station and the first terminal are called. The service flow between the two terminals is called the second service flow, and the service flow between the base station and the third terminal is called the third service flow. When the same ROHC algorithm is applied and operated for each service flow, when a new service flow for a new terminal is generated, the same ROHC algorithm is collided with the existing ROHC algorithm applied to the first to third service flows. That is, the new service flow for the new terminal must start in the IR state 300 with little compression to transition to the FO state 310 or the SO state 320 to collect information for restoring compression. However, due to the characteristics of the MBS service, the new service flow is affected by the ROHC algorithm applied to the existing service flows (first to third service flows).

Looking at the ROHC IR packet, the ROHC starts in IR state 300 in U mode. In the IR state 300, the IR packet is transmitted, but the IR packet is an ROHC packet which has not been compressed. Therefore, the IR packet contains all the information for the decompressor to decompress.

4 illustrates an example of applying the same ROHC algorithm to multiple service flows for an MBS service in the present invention.

Referring to FIG. 4, the base station 400 includes compressors 402, 404, and 406 for compressing headers in service flows, respectively, to generate MBS service flows with the terminals 410, 420, and 430, respectively. do. On the other hand, the terminals 410, 420, and 430 respectively include compression-restorers 412, 422, and 432 to recover the compressed packets from the base station 400.

In the present invention, when the MBS service flow is newly generated, an initial ROHC packet is transmitted through a second management connection identifier (hereinafter referred to as "SMC") 408 to apply the same ROHC. send. The SMC is a management connection generated for transmission of a Simple Network Management Protocol (SNMP) message and a Dynamic Host Configuration Protocol (DHCP) message between a terminal and a base station. The SMC is optionally generated between the terminal and the base station to transmit the corresponding packets. In addition, in the present invention, the initial ROHC packet is collectively referred to as the ROHC packet in which the first MBS service flow is generated and initially transmitted through the SMC.

On the other hand, the compressors 402, 404, 406 and compression-restorers 412, 422, 432 of the ROHC engine are mapped 1: 1 with the service flow as described above. Since the MBS service is a unidirectional service, no reverse channel is required. Therefore, when a MBS service flow to which ROHC is applied is generated, the value of "Feedback For" is not set, and the SMC is used as a channel for sending an initial ROHC packet. When the MBS service flow is generated, there is no "Feedback For" value for each channel parameter, and to indicate the SMC (Secondary Management Connection) instead of the channel's SFID (Service Flow ID). TLV (Type Length Value) is added to the standard. Table 2 below is included in the ROHC parameter (per-channel parameter) transmitted in the DSx process for generating the MBS service.

Type Length Value Scope [145/146]. 47.6 One 0x01: SMC for ROHC Feedback Channel DSA-REQ, DSA-RSP

Table 1 shows the TLV encoding for the ROHC SMC channel.

In FIG. 4, it is assumed that the terminals 410, 420, and 430 receive the same broadcast at the MBS Zone ID 2. In this case, the terminals 410, 420, and 430 generate a service flow including the MBS Zone ID and the MCID through the DSx process. In this case, the service flow is a service flow to which ROHC is applied. The MBS service is a downlink unidirectional service, and the compressors 402, 404, and 406 are generated in the base station, and the compression-restorers 412, 422, and 432 are generated in the terminal.

At the base station 400 receiving the data from the MBS content server, each compressor 402, 404, 406 will compress the header and send it to the terminals 410, 420, 430. The ROHC packet, which is initially compressed and transmitted, will be an IR packet (a packet transmitted in the IR state 300 in FIG. 3), which is different from the conventional MBS data transmission method through each terminal 410, through the SMC 408. 420, 430. If the terminal 410, 420, 430 does not receive a predetermined number of initial ROHC packets through the SMC (414, 424, 434) it will not decompress. Compressed packets other than the initial ROHC packet are not received, and if received, they are discarded without being decompressed.

Multiple service flows can be created per terminal at the same time, and the compressor operates differently for each service flow, so that the initial ROHC packet can be transmitted through the SMC as defined in <Table 2> and <Table 3>. Use an initial ROHC packet.

11111001 SFID Feedback Date

11111001 SFID IR Packet

11111001 (1 byte) is not yet used to indicate another ROHC packet type (RFC 4995). Therefore, 11111001 (1 byte) is added to indicate that the initial ROHC packet is transmitted through the SMC, and then the SFID is attached to the initial ROHC packet (see Table 3 above) to the corresponding compressor / compression-restorer.

For example, in FIG. 4, the base station 400 sends an initial ROHC packet to the terminals 410, 420, and 430 by an optimistic approach count through the SMC 408. At this time, the initial ROHC packet includes mode information and ROHC state information of the compressed compressor. ROHC IR Packet is a part that changes a lot when compressed is defined as a dynamic part and transmitted. The initial ROHC packet uses the "Reserved" part 3 bits to represent the compressor state information. 000 represents an IR state, 0001 represents an FO state, and 010 represents an SO state. The received ROHC IR Packet decompresses the Decompressor and transmits it to the upper layer.

When the terminal receives the ROHC IR packet by the optimistic access count through the SMC 408, the preparation of the compression-restorer 412, 422, 432 for decompression is completed and the compression-restorer 412, 422 of the terminal is finished. , 432 sends a ROHC Feedback Packet (see Table 2) to the base station 400 via the SMCs 414, 424 and 434 to inform the base station that it is ready to decompress. The base station 400 receiving this no longer transmits the ROHC IR Packet through the SMC. The compression-restorer 412, 422, 432 of the terminal views the mode and state of the compressors 402, 404, 406 through the initial IR packet, and the compression-restorer 412, 422, Transition to mode and state of 432). After this process, the compression-restor 412, 422, 432 may decompress the broadcast MBS data burst. From the next step, it works the same as normal ROHC operation.

5 illustrates an operation of a base station for applying ROHC to an MBS service in a broadband wireless communication system according to an embodiment of the present invention.

Referring to FIG. 5, when the MBS service flow is added in step 500, the base station proceeds to step 502 and generates an MBS having a ROHC service flow as shown in Table 3 above. That is, as shown in FIG. 4, the compressors 402, 404, 406 and the compression-restorers 412, 422, 432 of the ROHC engine are mapped 1: 1 with the MBS service flow.

In step 504, the base station registers the newly created compressor in the virtual compressor list. All base stations with the same MCID of the same MBS Zone ID are synchronized, and even though the service flows are different, all compressors should compress the same and transmit the same ROHC packet. Therefore, physically differently produced compressors should be logically bundled into one compressor. This is referred to as a virtual compressor in the present invention. The virtual compressor has no special function as a virtual compressor. Just manage the compressors and keep them motivated. The mode and state of the virtual compressor become the ROHC mode and state of other compressors by sharing a database between the virtual compressor and the general compressor. This allows all compressors to behave logically as a single compressor. The location of the virtual compressor is where the service flow is managed.

Thereafter, the base station transmits an IR packet through the SMC in step 506 (see Table 3 above).

11111001 (1 byte) is not yet used to indicate another ROHC packet type (RFC 4995). Therefore, 11111001 (1 byte) is added to indicate that the initial ROHC packet is transmitted through the SMC, and then the SFID is attached to the initial ROHC packet (see Table 3 above) to the corresponding compressor / compression-restorer.

After receiving the feedback packet for the IR packet transmitted through the SMC in step 508, the base station proceeds to step 510. If the base station does not receive the feedback packet, the base station proceeds to step 506 to continue transmitting the IR packet through the SMC. .

In step 510, the base station stops transmitting IR packets through the SMC and copies the database of the virtual compressor to the new compressor.

Thereafter, the base station performs a general operation in step 514.

The base station then terminates the procedure of the present invention.

6 illustrates an operation of a terminal for applying ROHC to an MBS service in a broadband wireless communication system according to an embodiment of the present invention.

Referring to FIG. 6, in step 600, the terminal receives IR packets through the SMC and checks whether a predetermined number of IR packets are received through the SMC in step 602. This is to receive decompression information from a certain number of received IR packets.

Thereafter, in step 604, the terminal transmits a ROHC Feedback Packet to the base station indicating that a predetermined number of IR packets have been received through the SMC.

Thereafter, the terminal updates the mode and state of the compression restorer in step 606.

The terminal then terminates the procedure of the present invention.

7 illustrates an apparatus for applying ROHC to an MBS service in a broadband wireless communication system according to an embodiment of the present invention. The device may be a terminal or a base station.

Referring to FIG. 7, the apparatus includes an RF processor 701, an analog / digital converter 703, an OFDM demodulator 705, a decoder 707, a message processor 709, and a controller 711. ), ROHC engine 713, ROHC mode selector 715, message generator 717, encoder 719, OFDM modulator 721, Digital / Analog Converter 723, RF processor ( 725).

First, the time controller 729 controls the switching operation of the switch based on frame synchronization. For example, if a signal is received, the time controller 729 controls the switch to connect the antenna and the RF processor 701 of the receiver. In addition, when the signal transmission period, the switch is controlled so that the antenna and the RF processor 1125 of the transmitting end are connected.

During the reception period, the RF processor 701 frequency down modulates a radio frequency (RF) signal received through an antenna into a baseband analog signal. The analog / digital converter 703 converts an analog signal provided from the RF processor 701 into a digital signal and outputs the digital signal. The OFDM demodulator 705 converts the time domain signal provided from the analog-to-digital converter 703 into a signal of the frequency domain by performing Fast Fourier Transform. The decoder 707 selects data of subcarriers to be actually received from data in the frequency domain provided from the OFDM demodulator 705, and demodulates the selected data according to a predetermined modulation level (MCS level). And decoded and output.

The message processor 709 decomposes the control message provided from the decoder 707 and provides the result to the controller 711. For example, it decomposes an IR packet from a base station and decomposes an IR feedback packet from a terminal.

The controller 711 performs overall control of the base station (or terminal) and controls the ROHC algorithm according to the result provided from the message processing unit 709. It also controls the MBS service.

The ROHC engine 713 receives ROHC mode and state information from the ROHC mode selector 715 for the MBS service flow generated by the controller 711 and performs header compression / decompression in the corresponding mode and state. .

The ROHC mode selector 715 operates the compressor of the ROHC engine 713 in U mode because the MBS service is a one-way service. In the case of the same broadcast, compressors generated for each service flow are managed as one virtual compressor, and all compressors belonging to the same service perform the same operation. In other words, the ROHC operates in the same state in the same U mode. In addition, all of the compressed and transmitted ROHC packets are the same. As a result, all terminals listening to the same broadcast receive the same compressed ROHC packet, which makes it possible to apply the ROHC to the MBS service. During the DSx process for the new terminal to listen to the broadcast, the generated compressor is included in the virtual compressor list (registering the generated SFID), and is changed to the mode and state of the virtual compressor. The added compressor then transmits the ROHC IR packet defined to the terminal through the SMC. At this time, the mode and state information of the virtual compressor is transmitted. When the base station receives the ROHC Feedback Packet from the terminal through the SMC, the base station no longer transmits the ROHC IR packet through the SMC. When the compressor receives the Initial ROHC Feedback Packet transmitted by the terminal through the SMC, the database of the virtual compressor is copied to the newly registered compressor and synchronized with other compressors, thereby transmitting the same ROHC packet as other compressors. The terminal receiving the compressed MBS data discards all until the ROHC feedback packet is transmitted through the SMC.

The message generator 717 generates a message using the control information provided from the controller 711. For example, an IR packet is generated at the base station and an IR feedback packet is generated at the terminal.

The encoder 719 codes and modulates the signal provided from the message generator 717 according to a predetermined modulation level (MCS level).

The OFDM modulator 721 converts the frequency domain signal provided from the encoder 719 into a time domain sample signal by performing an inverse fast Fourier transform. The digital-to-analog converter 723 converts a sample signal provided from the OFDM modulator 721 into an analog signal and outputs the analog signal. The RF processor 725 frequency-modulates the baseband signal provided from the digital-to-analog converter 723 into a radio frequency (RF) signal and transmits it through an antenna.

In the above-described configuration, the controller 711 is a protocol controller, and controls the message processor 709, the message generator 717, the ROHC engine 713, and the ROHC mode selection 715. That is, the controller 711 may perform the functions of the message processor 709, the message generator 717, the MAC version checker 713, and the ranging controller 715. In the present invention, it is separately configured to describe each function separately.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

1 is a broadband wireless communication system for a multicast and broadcast service (MBS) service;

2 is a general MAC PDU configuration diagram,

3 is a state transition diagram of the compressor in U mode,

4 is an exemplary diagram for applying the same ROHC algorithm to multiple service flows for MBS services in the present invention;

5 is a flowchart illustrating an operation of a base station for applying ROHC to an MBS service in a broadband wireless communication system according to an embodiment of the present invention;

6 is a flowchart illustrating an operation of a terminal for applying ROHC to an MBS service in a broadband wireless communication system according to an embodiment of the present invention;

7 is a diagram illustrating an apparatus for applying ROHC to an MBS service in a broadband wireless communication system according to an exemplary embodiment of the present invention.

Claims (4)

A method of operating a base station for applying Robust Header Compression (ROHC) to a Multicast & Broadcast Service (MBS) service in a broadband wireless communication system, When a service flow is generated in the MBS service, transmitting a predetermined number of initial ROHC packets through a second management connection identifier (SMC); Receiving a feedback packet for the predetermined number of initial ROHC packets; And after receiving the feedback packet, performing a general operation on the synchronized ROHC packet. A method of operating a terminal for applying Robust Header Compression (ROHC) to a Multicast & Broadcast Service (MBS) service in a broadband wireless communication system, Receiving a predetermined number of initial ROHC packets through a second management connection identifier (SMC); Transmitting a feedback packet for the predetermined number of initial ROHC packets; And after transmitting the feedback packet, performing a general operation on a synchronized ROHC packet. A base station for applying ROHC (Robust Header Compression) to a MBS (Multicast & Broadcast Service) service in a broadband wireless communication system, A transmitter for transmitting a predetermined number of initial ROHC packets through a second management connection identifier (SMC) when a service flow is generated in the MBS service; A receiver for receiving feedback packets for the predetermined number of initial ROHC packets; And a ROHC engine unit configured to perform a general operation with the synchronized ROHC packet after receiving the feedback packet. A terminal for applying Robust Header Compression (ROHC) to a Multicast & Broadcast Service (MBS) service in a broadband wireless communication system, A receiver for receiving a predetermined number of initial ROHC packets through a second management connection identifier (SMC), A transmitter for transmitting a feedback packet for the predetermined number of initial ROHC packets; And a ROHC engine unit configured to perform a general operation with the synchronized ROHC packet after transmitting the feedback packet.

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